Linguistic irregularities in number naming systems, such as the inversion of number words, affect the processing of Arabic numerals. Recently, it has been claimed that there is even a syntactic representation of number words. participant investigate the neurofunctional correlates of the syntactic processing of number words by examining different levels of place-value processing in a study with two complementary successive phases (Group 1 and Group 2) in healthy adults. In the first phase with Group 1, participant evaluate the unit-decade compatibility effect (UDCE) in two-digit magnitude comparisons. In the second phase with Group 2, participant investigate the carry-over effect in two-digit addition problems.